XCOM problem

[SX-ALY]

Hi all

I post that for a friend.

He got an XCOM 760 radio intercom and since he can receive loud and clear has problem transmitting.
It seems that he has limited power output, and no voice at all..
When he is very close to an airport VHF receiver (on taxiway for example) he can transmit and power on the runway lights but has NO voice on transmitted signal at all.
Seems that there is RF frequency carrier(limited power though) but no modulation(voice) at all.
Antenna is a bent whip probably a COMANT 122 but not 100% sure.

Any ideas as from where to start searching for a problem?

Thanks in advance
Thanos

 

[aerhed]

Bypass

You might try to connect a microphone jack as directly as you can to the xcom and use a hand mike. Temporary elimination of stick wiring, etc. may lead you to the problem, i.e. radio internal, wiring, or wiring and antenna cable & ground. Almost sounds like 2 problems.

 

[Geico266]

RocketBob is the local XCOM expert. I'm sure he will be a lone shortly, but my guess is the antenna. Have him clean all the connections and the antenna itself.

 

[rocketbob]

Sounds like a mic circuit wiring issue, but not enough info presented to go by.

I'm one of the factory service reps and can check out the radio for you, if you send it to me.

email me at [email protected] if you would like to send the radio to me to check out.

 

[SX-ALY]

You might try to connect a microphone jack as directly as you can to the xcom and use a hand mike. Temporary elimination of stick wiring, etc. may lead you to the problem, i.e. radio internal, wiring, or wiring and antenna cable & ground. Almost sounds like 2 problems.

RocketBob is the local XCOM expert. I'm sure he will be a lone shortly, but my guess is the antenna. Have him clean all the connections and the antenna itself.

Sounds like a mic circuit wiring issue, but not enough info presented to go by.

I'm one of the factory service reps and can check out the radio for you, if you send it to me.

email me at [email protected] if you would like to send the radio to me to check out.

Thanks all for the quick reply.

What he likes and i agree on that, is to do a little troubleshooting before send the unit for repair. If more info needed then i can post it here.
About the mic now i have to add that intercom works OK since he can talk and listen to his passenger. Is that an indication that mic and mic's connections work fine?

Also he told that he couldn't have the airport's lights ON from a mile or two distance but he make it when he was taxiing back.(weak power?).
You can hear the noise on the airport's receiver when someone click on PTT switch for the lights but if he tries to talk there is no voice.

Thanos

 

[SX-ALY]

Sounds like a mic circuit wiring issue, but not enough info presented to go by.

I'm one of the factory service reps and can check out the radio for you, if you send it to me.

email me at [email protected] if you would like to send the radio to me to check out.

Hi Bob and thanks
Do you think that is mic wiring issue even though the intercom works fine?

Thanos

 

[rocketbob]

It is possible that the mic lines are reversed between the pilot PTT and the passenger PTT. If the pilot PTT button is pressed, and the mic is connected to the passenger mic line, it will not allow audio thru the mic when transmitting. As a quick check you might want to try plugging the headset in on the passenger side, and transmit using the pilot PTT button, and vice-versa.

Also you need to make sure sidetone is enabled.

 

[SX-ALY]

It is possible that the mic lines are reversed between the pilot PTT and the passenger PTT. If the pilot PTT button is pressed, and the mic is connected to the passenger mic line, it will not allow audio thru the mic when transmitting. As a quick check you might want to try plugging the headset in on the passenger side, and transmit using the pilot PTT button, and vice-versa.

Also you need to make sure sidetone is enabled.

I m' going to tell him to give it a try.
Comm used to work before without a problem. I mean is not a new installation that has a connection problem (like reversed connections etc.) unless there is a short in the cables somewhere that made the reversing.

thanks
Thanos

 

[SX-ALY]

It is possible that the mic lines are reversed between the pilot PTT and the passenger PTT. If the pilot PTT button is pressed, and the mic is connected to the passenger mic line, it will not allow audio thru the mic when transmitting. As a quick check you might want to try plugging the headset in on the passenger side, and transmit using the pilot PTT button, and vice-versa.

Also you need to make sure sidetone is enabled.

The above didn't work out.

Also he did reset the unit to defaults. ... Nothing
He did check antenna connection and looks OK. I told him to clean the antenna itself and to make sure that Sidetone is ON (which is the default after the reset but just in case).

Bob, i gave him your email address and he is going to email you directly. His name is Dale.

Thanks

Thanos

 

[Michael Coates XCOM]

It could be a modulator fet failure if its transmitting carrier but no voice, it reallys needs a power meter connected to be sure.

 

[SX-ALY]

XCOM problem SOLVED

Bob sent a unit to my friend Dale for FREE to try it and we test that yesterday and everything working OK.
Defective unit is going back to Bob.
I would like to thanks anyone involved in that issue, Bob, Michael from XCOM, Doug for this forum, and everyone that tried to help with one way or another.

Thanks again Bob

Thanos
Dale